1. Field of the Invention
The subject invention relates to hemodynamic pressure monitoring and similar systems, and to methods and apparatus for flushing catheters and similar devices at different flow rates.
2. Disclosure Statement
This disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness, and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments subsequent in time or priority.
A main field of utility of the subject invention is apparent from the following patents dealing with catheter flushing apparatus and similar systems and being herewith incorporated by reference herein.
In particular, U.S. Pat. No. 3,675,891, by G. S. Reynolds et al, issued July 11, 1972, shows catheter flushing apparatus embodying a small block having therein passages for a flushing solution, with a flow resistor limiting the flushing to a small amount being located in one of the passages, and a valve being located in another passage connected by a bypass to the first passage for fast flushing upon manual pulling of a valve stem extending from a valve of resilient material through and beyond a wall of the flushing block. In practice, a certain safety factor thus gained tends to be encumbered by the disadvantage that typically both hands are required for actuation of the flushing valve. Moreover, it has been pointed out that the protruding stem of that device is subject to entanglement in tubing, bedding and the like, resulting in possible undesired opening of the valve or breakage of the valve stem so as to preclude proper operation of the device. It has also been pointed out that the valve stem can be broken by pulling the stem to one side or the other rather than longitudinally, and that the valve has been found occasionally to fail in the open position. Also, the presence in or at the liquid path of resilient material of which the valve body and a tubular extension thereof are made tends to introduce a dampening factor affecting a pressure sensing capability and quality frequently required in hemodynamic monitoring systems.
This problem is also present with the flow regulating devices for arterial catheter systems disclosed in U.S. Pat. No. 4,192,303, by J. E. Young et al, issued Mar. 11, 1980, and its continuation-in-part U.S. Pat. No. 4,278,083, issued July 14, 1981 and its division, U.S. Pat. No. 4,337,770, issued July 6, 1982, as well as with the continuous flushing apparatus disclosed in U.S. Pat. No. 4,245,636, by S. L. Sparks et al, issued Jan. 20, 1981. In particular, these flow regulating devices and flushing apparatus employ an outer flexible conduit which is squeezed for fast flushing in circumvention of a capillary passage. Moreover, those flow regulating devices and flushing apparatus appear exposed to the danger of unintended flushing through accidental depression of the outer flexible conduit, be it by a patient turning in bed or through another disturbing agency.
The latter problem may be somewhat alleviated in the first embodiment disclosed in U.S. Pat. No. 4,291,702, by J. E. Cole et al, issued Sept. 29, 1981 and in the corresponding embodiment of the related U.S. Pat. No. 4,341,224, by J. D. Stevens, issued July 27, 1982. In particular, those embodiments employ a design in which an actuator knob attached to an actuator shaft has to be pulled outwardly for the opening of a fast-flush valve. That design, however, again appears to require both hands for actuation of the valve. In an apparent effort to alleviate that problem, both of the latter patents propose second embodiments having a lever design for one-hand operation.
Unfortunately, such design appears, however, exposed to accidental actuation of the flushing valve. Moreover, the flushing apparatus of both of these patents require the presence of pressure pulse dampening elastomeric parts at the fluid path in the flushing apparatus.
The latter problem appears to be alleviated in a disposable flush device, sold by Graphic Controls, as Part No. 5100 and employing a helically coiled wire spring for biasing the flush valve to a closed position In that device, a capillary passage extends axially through the central valve body for flushing at a seeping flow rate when the valve is closed. Upon depression of an external fast flush button against the bias of the mentioned helical spring, the valve is opened and liquid can flush therethrough to the catheter, thereby bypassing the centrally disposed capillary passage which, of course, remains intact throughout the flushing operation, as well as before and thereafter.
The fast flush button in the latter device is disposed between two upwardly projecting portions of a lateral enclosure having a saddle-shaped circumference, whereby diametrically opposed portions of the fast flush button appear, nevertheless, to be exposed to accidental contact by fingers and objects and thereby to accidental actuation and consequent unintended release of the flushing operation.
Neither related nor different fields of endeavor appear to offer solutions for these problems. For instance, U.S. Pat. No. 3,298,367, by R. I. Bergman, issued Jan. 17, 1967, proposes apparatus for administering parenteral liquids employing capillary tubes connected in parallel between spaced headers. Conversely, U.S. Pat. No. 4,198,031, by F. D. Ezekiel et al, issued Apr. 15, 1980, proposes an automatic air deflation valve having an air flow channel extending longitudinally through a housing and a deformable diaphragm in an air deflection port extending outwardly from the channel and having a central aperture extending through the thickness thereof. The diaphragm deforms according to applied air pressure to automatically adjust the size and shape of the aperture, thus producing a constant air deflation rate therethrough.
U.S. Pat. No. 1,005,409, by H. T. Burns, issued Oct. 10, 1911, discloses a valve having a restricted passage for a continuous supply and a larger passage for a temporary increased supply with an internal spindle located in a threaded external spindle, both of which are subject to accidental actuation in practice. U.S. Pat. No. 1,983,227, by E. L. Hall et al, issued Dec. 4, 1934, discloses a gas pilot light control which is also vulnerable to accidental actuation.
On the other hand, the piston and flush valve disclosed in U.S. Pat. No. 2,181,900, by J. D. Langdon, issued Dec. 5, 1939, appears to require special tools for its adjustment and operation.
Further proposals appear to have one or more of the above mentioned disadvantages and to be of a generally too complex design for present purposes, as may be seen from U.S. Pat. No. 2,229,903, by L. H. Schmohl et al, issued Jan. 28, 1941, and disclosing a metering valve with several adjustable plugs, U.S. Pat. No. 2,411,667, by L. D. Mowrey, issued Nov. 26, 1946, and disclosing a bottom hole regulator including a valve mounted in a tubular body on a stem between a guide member and a valve seat, U.S. Pat. No. 2,655,170, by W. T. Ferguson, issued Oct. 13, 1953, and disclosing an air vent for water systems employing hydroscopic elements, U.S. Pat. No. 2,955,614, by R. E. Meynig, issued Oct. 11, 1960, for a constant tubing pressure choke for maintaining substantially constant fluid flow irrespective of variations in the pressure condition of a well pipe, U.S. Pat. No. 3,107,894, by F. R. Quinn, issued Oct. 22, 1963, for a snap action flow control valve with a Venturi formed between an orifice and a conical valve plug, U.S. Pat. No. 3,115,156, by F. R. Mortimer, issued Dec. 24, 1963, for a fluid pressure surge damper particularly for braking systems, U.S. Pat. No. 3,118,647, by W. H. Hasty, issued Jan. 21, 1964, for a valve assembly employing magnetic valve elements, U.S. Pat. No. 3,428,366, by C. H. Harvey, issued Feb. 18, 1969, for a flow control arrangement having a transverse channel for minimum operational flow in an actuable gate member, U.S. Pat. No. 3,474,816, by L. D. Burgess, issued Oct. 28, 1969, for purgeable gas pressure regulators, U.S. Pat. No. 3,877,428, by C. E. Seagle, issued Apr. 15, 1975 for a variable infusion control device providing a capillary flow path for administration of fluid parenterally at essentially uniform flow rates, and U.S. Pat. No. 4,173,296, by W. A. Marshall, issued Nov. 6, 1979, for apparatus for mixing and dispensing a beverage, including a mixing orifice system.
SUMMARY OF THE INVENTION
It is a general object of this invention to overcome the disadvantages and to meet the needs set forth in or apparent from the above disclosure statement, in any of the mentioned patents incorporated by reference herein, or in any other part hereof.
It is a germane object of this invention to provide solutions based on new approaches to the flushing, monitoring and operation of catheter systems.
It is a related object of this invention to provide improved flushing methods and apparatus.
It is also an object of this invention to increase the safety and reliability of operation of catheter and other flushing and monitoring systems and the well-being and safety of people relying thereon.
It is also an object of this invention to simplify design, construction and manufacture of catheter flushing and/or monitoring devices and of similar apparatus.
It is also an object of a particular aspect of this invention to dispense with the capillary tube heretofore consistently employed in catheter flushing devices for the purpose of providing a seeping flow rate.
Other aspects of this invention will become apparent in the further course of this disclosure.
From a first aspect thereof, the subject invention resides in a method of, or in apparatus for, flushing, or making a valve enabling flushing of a catheter intermittently at a flushing flow rate higher than a seeping flow rate with the aid of a valve connectable between a supply of flushing liquid and the catheter and having a valve stem and a manually actuable valve operator on an end portion of the valve stem and engageable by a human finger for depression from a rest position, in which the valve is closed to flushing at the flushing flow rate, to a depressed position in which the valve is open for flushing of the catheter at the flushing flow rate.
According to this first aspect thereof, the invention resides in the improvement comprising, in combination, the steps of, or means for, making the operator of an elastic material providing an integral elastic sleeve about the end portion of the valve stem, employing the integral elastic sleeve for biasing the operator to the rest position before and after manual actuation against the bias of the elastic sleeve to the depressed position, and protecting the operator against accidental depression at all points thereof by completely surrounding the operator with a shield surpassing the operator around its entire circumference so as to require the human finger to penetrate into the shield for engagement of the operator prior to depression from the rest position against the bias of the elastic sleeve for an opening of the valve.
From a second aspect thereof, the invention resides in the improvement comprising in combination, the steps of, or means for. providing the valve stem with a snap-on connector end at the operator, providing the operator with a retainer and providing the retainer with a snap-on connection means for retaining the operator at the valve stem via the snap-on connector end, and retaining the operator at the valve stem with the retainer connected via the snap-on connection means to the snap-on connector end.
From another aspect thereof, the subject invention resides in a method of or in apparatus for, flushing, or making a valve enabling flushing of a catheter continually at a seeping flow rate through a capillary passage and intermittently at a higher flushing flow rate upon an opening of said capillary passage.
According to this latter aspect, the subject invention resides more specifically in the improvement comprising, in combination, the steps of, or means for, providing a manually actuable operator for intermittently opening said capillary passage, and protecting the capillary passage against accidental opening by completely surrounding the operator with a shield surpassing the operator around its entire circumference.
From yet another aspect thereof, the invention resides in apparatus for flushing a catheter continually at a seeping flow rate through a capillary passage and intermittently at a higher flushing flow rate, and, more specifically, resides in the improvement comprising, in combination, a flushing liquid outlet on the apparatus connectable to the catheter, an outlet passage extending in that apparatus from the capillary passage to the outlet and means for sensing liquid pulsations in the outlet passage between the capillary passage and the outlet, including a built-in transducer integral with the apparatus and having a pressure sensitive component in the apparatus only near the liquid outlet opposite the capillary passage, for sensing liquid pulsations in the outlet passage in the apparatus.
From a related aspect thereof, the invention resides in a combination including a flushing liquid outlet on the apparatus connectable to the catheter, an outlet passage extending in the apparatus from the above mentioned capillary passage to the outlet and including a concave cavity increasing in diameter from a bottom region to a wider top opening facing the capillary passage, and means for sensing liquid pulsations in the outlet passage and the outlet, including a built-in transducer integral with the apparatus and having a pressure sensitive component at the bottom region of the concave cavity, for sensing liquid pulsations in the outlet passage.